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Constraints on the timing of debris-covered and rock glaciers: An exploratory case study in the Hólar area, northern Iceland
Geomorphology ( IF 3.9 ) Pub Date : 2020-07-01 , DOI: 10.1016/j.geomorph.2020.107196
José M. Fernández-Fernández , David Palacios , Nuria Andrés , Irene Schimmelpfennig , Luis M. Tanarro , Skafti Brynjólfsson , Francisco J. López-Acevedo , Þorsteinn Sæmundsson , A.S.T.E.R. Team

Abstract Eighteen samples for 36Cl Cosmic-Ray Exposure (CRE) dating were taken from glacially polished bedrocks, moraine boulders, fossil/active rock glaciers and debris-covered glaciers in Fremri-Grjotardalur and Holadalur cirques in the Viðinesdalur, Hofsdalur and Heðinsdalur valleys, close to Holar village, in the Trollaskagi peninsula, northern Iceland. Boulder sampling was preceded by a study of the boulder stability with the twofold aim of: ensuring that the surfaces to be sampled were stable enough for the reliable application of CRE dating, and to better understand the relation between the glacier dynamics and exposition history. The results show that the glaciers which occupy the valleys in Trollaskagi began their retreat around 16 ka. Later, the glaciers advanced again around 11 ka within the cirques, and small moraines were formed. Thereafter, these small glaciers retreated and evolved into rock glaciers as debris from paraglacial processes accumulated on the glacier surface. The fronts of these rock glaciers stabilized definitively shortly after their formation and became eventually fossil after the melting of their internal ice. New rock glaciers and debris-covered glaciers formed afterwards, which still have internal ice at present, although their current dynamics are mostly related to subsidence. The stabilization of these rock glaciers and debris-covered glaciers is dated to the period between 7 and 3 ka, although they may have been reactivated during cold neoglacial periods. This research demonstrates the potential interest in applying CRE dating methods to debris-covered glaciers and rock glaciers to determine their origin, evolution and phase of cessation of internal movement until they finally lost their internal ice and became fossil.

中文翻译:

碎片覆盖和岩石冰川的时间限制:冰岛北部霍拉尔地区的探索性案例研究

摘要 18 个用于 36Cl 宇宙射线曝光 (CRE) 测年的样品取自 Viðinesdalur、Hofsdalur 和 Heðinsdalur 的 Fremri-Grjotardalur 和 Holadalur 冰斗的冰川抛光基岩、冰碛巨石、化石/活动岩石冰川和碎片覆盖的冰川前往位于冰岛北部 Trollaskagi 半岛的 Holar 村。巨石采样之前进行了巨石稳定性研究,其双重目的是:确保要采样的表面足够稳定,以便可靠地应用 CRE 测年,并更好地了解冰川动力学与展览历史之间的关系。结果表明,占据 Trollaskagi 山谷的冰川在 16 ka 左右开始退缩。后来,冰圈内的冰川在 11 ka 左右再次前进,形成了小冰碛。此后,这些小冰川退缩并演变为岩石冰川,因为冰河过程产生的碎片堆积在冰川表面。这些岩石冰川的锋面在形成后不久就稳定下来,并在其内部冰融化后最终成为化石。之后形成的新岩石冰川和碎屑覆盖的冰川,目前仍存在内部冰,但其目前的动态主要与沉降有关。这些岩石冰川和碎片覆盖的冰川的稳定可追溯到 7 到 3 ka 之间,尽管它们可能在新冰期寒冷时期重新激活。这项研究证明了将 CRE 测年方法应用于碎片覆盖的冰川和岩石冰川以确定其起源的潜在兴趣,
更新日期:2020-07-01
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